ES2374723T3 - COMPOSITE BAND TO FORM A HELICOIDAL TUBE AND ITS MANUFACTURING PROCEDURE. - Google Patents

Abstract

Band (10) of composite material, roll-up to form a helical tube for transporting fluids, whose composite band (10) comprises: an elongated plastic band (11) having a part of the base (12) with the lower side that defines an inner face and an upper side that defines an outer face; at least one longitudinally extending rib (20), which protrudes from the outer face of the base part (12); and an elongated reinforcement band (30) that extends longitudinally and is laterally supported by the rib (20), the reinforcement band (30) having a height measured in orthogonal direction with respect to the base (12) and a thickness measured in a direction parallel to the base part (12), the reinforcement band (30) being oriented substantially perpendicular to the base part (12), and the reinforcement band (30) having a relationship of height to thickness of at least three to one, the inner face forming a continuous surface below the reinforcement band (30), in which, when rolled into a helical tube, the reinforcement band (30) reinforces the tube against radial crushing loads and the inner face separates the reinforcement band (30) from the fluid located inside the tube.

Description

Composite band reellable to form a helical tube and its manufacturing procedure

SECTOR OF THE INVENTION

The invention relates to a composite band that can be wound to form a helical tube for transporting fluids, to a composite tube wound helically manufactured from a composite band and to a method of manufacturing a plastic tube reinforced with helically wound steel.

BACKGROUND

It is well known that tubes of plastic material can be made by helically winding a band of plastic material having a series of ribs directed upwardly spaced apart from one another, which extend longitudinally with respect to the band, at room temperature, or at a temperature elevated, in which the plastic material becomes more flexible. This helically wound tube shape is already well known in the tube manufacturing industry and is described in patents by the applicant himself, concerning both the shape of the plastic band and the shape of the machine by which the tube or tubes from said bands.

For these tubes to work in high performance applications, in order to obtain the necessary degree of resistance, the thickness of the plastic walls must be quite important, as well as that of the ribs. Alternatively, the finished tubes or pipes can be reinforced with reinforcing or resistance increasing elements.

In applications where reinforced pipes or pipes are buried in a ditch or subjected to high earth loads, the resistance of the pipe or tube is of extreme importance.

The Australian patent of the applicant No. 607431 discloses a method of manufacturing a reinforced plastic tube using a reinforcement element located between the ribs, such that the flexural strength of the finished tube or pipe increases materially. The reinforcing element comprises a metallic element having a profile whose shape, in cross section is of U, the free ends of the reinforcing element being designed to engage below opposing flange formations of a pair of adjacent ribs to block from this way the metal band in position between the nerves and, in turn, reinforce the nerves and the finished tube.

The Australian patent of the applicant No. 661047 discloses improvements with respect to the aforementioned Australian patent No. 607431, to which reference has been made in the foregoing. The improvements are achieved by the provision of a reinforcing element, which has an inverted U-shaped part of the body or a V-shaped cross-section, which has a radial height greater than the height of the ribs, so that The effective external diameter of the composite tube increases substantially. This provides a more rigid tube.

The helically wound composite tubes of known type are formed in a multi-stage process. The plastic body is extruded and then helically wound to form a tube. Elongated reinforcing steel elements are laminated separately constituting a profile that provides the necessary stiffness (such as the shape of inverted U or V profiles referred to in the foregoing). The rolled steel profile is wound with a radius approximately that of the helically wound plastic body. Finally, the profiled reinforcing element or elements, provided with radius, are wound on the outside of the plastic tube to form a composite tube with the desired stiffness.

When the reinforcement elements that are disclosed in Australian patents Nos. 607431 and 661047 are used, the step of laminating the steel reinforcing element by adopting a radius that approximates that of the plastic tube, entails stressing the element Steel reinforcement beyond its elastic limit. This requires the application of considerable force during the winding process. In contrast, the winding of the extruded plastic profile, formed by a helical tube, generally requires much less force due to the material properties of the plastic.

It is an object of the invention to disclose a composite band that is prepared for winding forming a helical tube.

SUMMARY OF THE INVENTION

JP 09 310 788 A is directed to the problem of coating existing tubes having a square cross-section, such as a box-shaped channel. The invention described is intended to disclose a profile for the coating of an existing tube that is capable of maintaining a fixed or predetermined curvature at each corner of an existing tube that has a square cross section, or of another type. The profile that is disclosed is designed to be sufficiently flexible, so that it can be wound close to the corners of a covered box and, having a base, is not provided with a reinforcing element. He

5 reinforcing element is arranged in a coil spirally wound separately. This allows to achieve a reduced radius of curvature with the profile or band, before the reinforcement element is introduced to maintain said radius.

WO 93/07412 A discloses a metal band of composite type having a metal reinforcement element folded in the form of W. The profile folded in W has a central body part in the form of U or V

10 inverted. JP 64 087992 A discloses a spiral tube having a reinforcing material around it to improve its rigidity.

This objective is achieved by a composite band according to claim 1 and a helically wound composite tube according to claim 13. In addition, a method according to claim 16 is provided. The dependent claims relate to special embodiments of the invention. . DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION In the following drawings, several preferred embodiments of the invention are shown, in which: Figure 1 shows a sectional view of a composite band, according to a first embodiment of the invention. 20 Figure 2 shows a view with the disassembled parts of the band of Figure 1.

Figure 3 is a perspective view of the composite band shown in Figure 1. Figure 4 is a perspective view of a helically wound composite tube, from the profile shown. in figures 1 and 3.

Figure 5 shows a partial sectional view of the tube of Figure 4, the reinforcing element being observed. 25 Figure 6 is a perspective view showing the reinforcement element introduced in the profile.

Figure 7 shows a cross-sectional view of a composite band, according to a second embodiment of the invention. Figure 8 shows a cross-sectional view of adjacent turns of a composite band, according

with a third embodiment of the invention.

Figure 9 shows a cross-sectional view of a composite band, according to a fourth embodiment of the invention. Figure 10 shows a cross-sectional view of a composite band, according to a fifth

embodiment of the invention. Figure 11 shows a cross-sectional view of a composite band, in accordance with a sixth embodiment of the invention.

Figure 12 shows a cross-sectional view of a composite band, in accordance with a seventh embodiment of the invention. Figure 13 shows a cross-sectional view of a composite band, according to an octave

embodiment of the invention. Figure 14 shows a perspective view of a reel drive device for use with embodiments of the invention. 3

Referring to Figures 1 and 2, an elongated composite band 10 that can be wound to form a helical tube has been shown. The composite band 10 comprises an elongated plastic band 11 and an elongated reinforcing metal band 30. The plastic used for this embodiment of the invention is polyethylene, although other suitable plastics can be used.

The plastic band 11 has a part of the base 12 with a substantially flat side 14. A series of longitudinal ribs 20 protrude upwardly from the part of the base 12. In this embodiment, each rib 20 comprises a pair of parallel walls 22 and 24 extending longitudinally along the part of the base 12, defining a longitudinal groove 23. The groove 23 is sized and shaped to receive, in a fitted manner, the reinforcement band 30, as best shown in the figure 2.

A rib of plastic material 40 is arranged as a bridge over the gap between the upper ends of the walls of the ribs 22 and 24 to thus encapsulate the reinforcement band 30 completely. This prevents exposure of the reinforcement band 30 to the environment and, therefore, helps prevent corrosion.

In the first embodiment of the invention, a set of three longitudinal ribs 20 are disposed apart, according to the width of the band. Each rib 20 supports a corresponding flat, elongated metal reinforcement band 30. In other embodiments of the invention, a greater or lesser number of ribs and reinforcement bands can be used. The ribs 20 that support the elongated metal reinforcement strips 30 must not necessarily be continuous. The ribs 20 can have any shape as long as they support the vertically oriented reinforcing bands 30.

Referring to Figure 4, a helically wound composite tube has been shown, produced by helically winding the composite band shown in Figures 1, 2 and 3. The joint between adjacent edges 18 and 16 of adjacent turns of the band is seen better in the cross section of figure 1.

Comparing Figures 1 and 4, it is evident that the orientation of the reinforcement bands 30, with respect to the flat face 14 of the base part 12, remains substantially unchanged after the winding to form the tube. The portions of the ribs 20 provide a support for the reinforcing bands 30, especially during the winding of the band 10. During the winding of the band 10 to form a helical tube, the reinforcing bands 30 are curved about a substantially axis transverse to the band 10. This causes the plastic deformation of the reinforcement bands 30. The ribs 20 help prevent the reinforcement bands 30 from laterally crushing towards the base of the plastic band 12.

Figure 5 shows an arc-shaped part of a reinforcing element 30, after it has been curved for the winding of the tube shown in Figure 4. Small areas of undulation 32 are shown.

It is important that these undulating areas do not exist, or that they are relatively small. If there is an excess of undulations, the ability of the tube to resist radial crushing loads is compromised.

Also, it is important to keep the mass of the profile to a minimum, while at the same time maintaining the performance criteria to ensure that material costs are minimal.

The dimensions and shapes of the plastic band 12 and the elongated metal reinforcement bands 30 may vary according to the diameter of the tube to be rolled. The following table indicates a range of configurations suitable for tubes with an internal diameter between 300 and 600 millimeters.

The height, thickness and number of the reinforcing steel bands used are variables that influence the rigidity of the wound tube. With larger diameter tubes, the contribution of plastic to the rigidity of the tube is relatively small (<10%). With tubes of smaller diameter, the contribution of plastic to the rigidity of the tube is higher (approximately 30% for a tube with an internal diameter of 300 mm).

The height to thickness ratios of the reinforcement bands 30 are important for a number of reasons. Reinforcement bands with high height to thickness ratio are preferable from the point of view of tube stiffness and efficient use of the material, but this must be balanced against the instability that may result. The instability can cause the reinforcement bands 30 to deform laterally towards the base of the plastic strip 12, or they may cause excessive undulation (the phenomenon of undulation is shown in Figure 5).

The selection of a steel with an optimal Young's modulus (or tensile modulus) and elastic limit for this application, are also important. In the case where the elastic limit is excessive, the undulation phenomenon is more likely.

With the range of profiles described in the previous table and with a thickness range of the ribbed part from 1.4 to 1.8 mm, stable tubes with a relatively low weight and having excellent resistance to radial crush loads.

While the described embodiment uses flat, elongated, steel reinforcing bands, flat reinforcing bands constructed of other materials can also be used.

The addition of the reinforcement bands 30 to the elastic band 12 can also help in improving the behavior of the pressure tube. The composite bands described in the foregoing can also incorporate other elements to improve the pressure behavior of the wound tube. For example, sheets of fiber cloth (eg, fiberglass), plastic or steel can be arranged to improve the pressure performance of the tube. Any material that has a Young's modulus and strength superior to the plastic material of the band can be used. The sheet can be incorporated into the profile (band 12) in any suitable manner. For example, the sheet can be welded to the base of the band 12 or can be extruded into the head, within the base of the band 12.

An improved interconnection of the edge can also be achieved, to favor the pressure behavior of the tube. Examples of profiles constructed for high pressure applications are shown in Figures 7 to 13.

Referring to Figure 7, a second embodiment of the invention has been shown in which the composite band 10 is extruded from PVC. A mechanical lock is provided by a male type edge element 16 and a female type edge element 18, formed from the plastic band 11. Reinforcement bands 30 of the type described above are also provided. This profile is extruded in the head encapsulating the reinforcing bands 30 when producing the composite band 10, obviating the need to add a sealing rib, as described above. A sheet 50 is incorporated into the base part of the band 11. The sheet 50 has a higher Young's modulus and greater strength than the PVC plastic band 11. When wound in a helical tube, this profile can provide a High pressure tube suitable for transporting pressurized fluids. While adjacent turns are not directly connected to each other, the thickness of the plastic and the design of the mechanical lock formed by adjacent edges 16 and 18 ensures that the tube is capable of withstanding significant internal pressures.

Figure 8 shows a cross section of two adjacent turns of the composite band 10, in accordance with a third embodiment of the invention. This composite band 10 comprises an extruded band of polyethylene 11, which has three ribs 20 extending from the part of the base 12, each rib 20 supporting a reinforcing strip 30. A fourth rib 21 is also provided that supports a fourth element of reinforcement 31. The location of the fourth rib 21 and of the reinforcement band 31 is at the edge of the profile, to reinforce the tube wound along the gap between the sheet of adjacent turns. This gap 54 is shown in Figure 8.

By providing a reinforcement in the upper part of the blocking element between adjacent turns of the composite strip and over the area in which the sheet is discontinuous, a tube capable of withstanding high pressures can be produced.

A fourth embodiment of the invention is shown in Figure 9. This embodiment of the invention is similar to the third embodiment, except that instead of arranging an additional rib and a reinforcing element on the joint area, the female locking section It has a thick wall to provide pressure capacity at the place where the sheet is discontinuous.

A fifth embodiment of the invention has been shown in Figure 10, in which no additional features are provided between adjacent turns to cover the area in which the sheets are discontinuous.

A sixth embodiment of the invention has been shown in Figure 11. With this embodiment of the invention, an additional sheet is welded in the edge area of the profile, as shown.

A seventh embodiment of the invention has been shown in Figure 12. This embodiment of the invention differs slightly from the above-described embodiment in that the additional sheet 55 is inserted during the tube winding process.

A final embodiment of the invention has been shown in Figure 13. With this embodiment of the invention, a continuous sheet is extruded into the head, into the base profile 12 and edge blocking areas, or is welded into the base afterwards. of extrusion.

Other embodiments of the invention can be achieved with the sheet attached to the base of the band 12 or incorporated into the base of the band 12.

Materials that have directional characteristics such as or within the sheet can be used. For example, oriented plastic film strips, which are resistant in the longitudinal direction, and weak in the transverse direction, can be used. These bands can improve the "circumferential" ("hoop") resistance of the wound tube.

Plastic bands resistant in the transverse direction and weak in the longitudinal direction can also be used.

In some applications, it will be desirable to form a sheet from two (or more) resistant plastic film bands in orthogonal directions to each other, thereby resulting in a composite material of high strength in all directions.

Examples of suitable materials that have directional characteristics include polyolefin sheets with high stretch. These sheets have a high proportion of molecules oriented in the same direction, which provides a high Young's modulus and elastic limit.

At present, helically wound composite tubes are formed in multi-stage operations. In general, a body of plastic material is extruded in a factory environment and then rolled onto a reel for transport. Next, the extruded strip is unwound from the reel and is passed through a winding machine that can also be located inside the factory, or alternatively it can be located in the place where the final tube is required. Finally, elongated bands of reinforcing steel are wound on the newly wound tube. In many applications, the steel reinforcing bands are pre-wound with a radius corresponding approximately to that of the helically wound plastic body before its introduction into the exterior of the plastic tube to form a composite tube with the necessary stiffness. Pre-bending of the reinforcement band is necessary in case the reinforcement elements have a high degree of stiffness, through the relevant bending axis.

The process of forming a helical tube from a profile, as described above, referring to figures 1, 2, 3, 5, and 6, is simplified since the reinforcement elements 30 are introduced in the band at any initial stage of manufacture and before the tube is rolled.

A process for the manufacture of a composite band 10, reusable to form a helical tube, is the one shown in Figure 6. A plastic band 11 is extruded presenting a substantially flat part of the base, and a set of Longitudinal ribs 20 separated from each other and parallel, vertical from the base part 12. Next, a series of elongated metal reinforcement bands 30 are introduced into the ribs 20. The reinforcement bands 30 have a height to thickness ratio, at least four to one and they are oriented substantially perpendicularly to the flat side 14 of the base part 12.

The introduction or insertion stage described in the foregoing takes place while the band of plastic material is arranged substantially flat. The reinforcement bands 30 are inserted straight, without any previous curvature. Finally, the plastic profiles 40 (as shown in Figures 1 and 2) are extruded over the upper portions of the ribs 20 to encapsulate the reinforcing bands 30.

Another method for manufacturing a roll-up composite band, to form a helical tube, is as follows. The plastic material and the steel band are introduced into the extrusion head, in which the two materials are integrated into a composite material profile, such as the composite band described in the above and shown in Figure 3. A Composite web formed by an extrusion head may be slightly different from the profile described above because of the fact that plastic profiles 40 (as shown in Figures 1 and 2) would not be necessary; instead, the extrusion head could be designed such that the steel band leaves the die completely encapsulated with plastic material.

Once the composite reinforcement band is produced, it is possible to wind the band directly into a helically wound tube, such as the tube shown in Figure 4 or, alternatively, the band can be rolled onto a reel for later use.

The ability to roll the composite profile onto a transport reel provides a number of advantages. For example, a single reel can be transported to the construction site, being positioned adjacent to the tube winding machine, located in the place where it is required to have the finished tube. The composite tube can be helically wound in a single operation, without the need for a significant amount of specialized equipment.

In order to be able to wind the straight composite band 12, without the reinforcing steel bands 30 causing their corrugation, it has been necessary to develop a new winding process. Existing conventional winding procedures create a trajectory of the band that reverses the curvatures of the band and then straightens it before the band passes to the reel hub. The reel is forced to rotate around a horizontal axis, the band being fed to the top or top side of the reel. For plastic bands without steel, this method is satisfactory.

However, when there is reinforcement steel of the web, this procedure is not suitable, since it causes the steel reinforcement to ripple 30.

Figure 14 shows a reel drive device 100 developed for winding the composite band 10 reinforced with steel. The reel 101 is supported with the ability to rotate about a horizontal axis 102. A guide 110 for the band is arranged to distribute the band 10, according to the width of the reel hub. An endless pneumatic cylinder 114, arranged on the rod 112, drives the belt guide 110 back and forth.

The winding method, developed for the steel reinforced band and shown in Figure 14, has a trajectory for the band that minimizes any load applied to it that could cause undulation. The path for the band on the reel 101 with this arrangement, is a straight path with respect to the bottom or bottom face 103 of the reel with the ribs directed downwards and, therefore, the part of the base 12 directed upwards, allowing that the band be curved with the correct orientation on the reel (the nerves directed outward, as they do in the wound tube).

The method of controlling the rotation speed of reel 101, developed for this new procedure is based

5 in the tension of the band 10 (motor torque). In addition to changing the winding procedure, the optimum dimensions of the reel hub have to be selected to prevent the ribs from undulating during the winding process. An initial cube dimension of 450 mm was tested and was suitable for some of the steel thicknesses, however, as the steel is thicker and with greater height, the size of the cube has to be increased. For the current band 10, prepared for tubes up to 750 mm in diameter, a size is required

10 of the 1000 mm cube.

The profiles of the second to eighth embodiments of the invention, as shown in Figures 7 to 13, can be fabricated using the procedure described above for the profile of the first embodiment of the invention shown in the Figures 1 to 6. The sheet can be introduced in a separate stage after the web has been extruded.

Claims (22)

1. Band (10) of composite material, roll-up to form a helical tube for transporting fluids, whose composite band (10) comprises: an elongated plastic band (11) having a part of the base (12) with the lower side defining an internal face and an upper side defining an external face; at least one longitudinally extending rib (20), which protrudes from the outer face of the base part (12); Y an elongated reinforcement band (30) that extends longitudinally and is laterally supported by the rib (20), the reinforcement band (30) having a height measured in orthogonal direction with respect to the base (12) and a measured thickness in a direction parallel to the base part (12), the reinforcement band (30) being oriented substantially perpendicular to the base part (12), and the reinforcement band (30) having a height ratio at a thickness of at least three to one, the inner face forming a continuous surface below the reinforcing band (30), in which, when wound by forming a helical tube, the reinforcement band (30) reinforces the tube against radial crushing loads and the inner face separates the reinforcement band (30) with respect to the fluid within the tube.

2.

 Composite web (10) according to claim 1, wherein the ratio of height to thickness is at least four to one.

3.

 Band of composite material (10) according to claim 2, wherein the rib comprises a pair of parallel walls (22, 24) that extend longitudinally along the base part (12), defining the rib ( 20), at least, in a longitudinal groove (23), in which the reinforcement band (30) is arranged, the band (30) being supported laterally by the groove walls (23).

Four.

 Composite web (10) according to claim 3, wherein the walls (22, 24) are oriented substantially perpendicularly to the base part (12).

5.

Composite web (10) according to claim 4, wherein the reinforcement web is continuous and has a co-extensive length with the plastic rib.

6.

 Composite band (10) according to claim 5, wherein the reinforcing band is completely encapsulated by plastic material, to prevent exposure to the environment.

7.

 Composite band (10) according to claim 6, wherein the plastic band has a set of longitudinal ribs that form grooves, which are separated from each other according to the width of the band, each rib supporting an elongated reinforcement band .

8.

 Composite web (10) according to claim 5, wherein the reinforcement web is constructed of a metal.

9.

 Composite web (10) according to claim 8, wherein the reinforcement web is constructed of steel.

10.

Composite web (10), according to any one of claims 1 to 9, whose web further comprises a flat sheet (50) that extends longitudinally and is attached to the base part, said sheet having a Young's modulus and resistance higher than those of the plastic band, so that once wound in the form of a helical tube, the sheet (50) improves the behavior of the tube under pressure.

eleven.

 Composite web (10) according to claim 10, wherein the sheet (50) comprises a fiber web.

12.

 Composite web (10) according to claim 11, wherein the fiber web comprises glass fibers.

13.

 Composite tube, helically wound from a band of composite material (10), the band of composite material (10) being according to any one of claims 1 to 12, the composite tube being helically wound characterized by the fact that the lower side of the base part of the composite web (10) forms the inside of the wound tube and the orientation of the reinforcing band, with respect to

The base part remains substantially unchanged after the winding of the web to form the tube.

14.

 Tube according to claim 13, wherein the reinforcing band (30) is continuous and has a coextensive length with the tube.

fifteen.

 Tube according to any one of claims 13 or 14, wherein the adjacent turns of the sheet (50) are not directly joined together.

16.

 Procedure for the manufacture of a tube of plastic material reinforced with helically wound steel, comprising the following stages:

extrusion of a plastic profile (11) having a part of the base (12) and a longitudinal rib (20) protruding from said base; insert a reinforcement band (30) with straight edges, elongated, into the rib (20), the metal band having (30) a height to thickness ratio of at least three to one and being oriented substantially perpendicular to the base part, thereby producing a straight band of composite material (10); helically winding the band of composite material (10) and interconnecting the adjacent edges of the adjacent turns of the band to form a helical tube.

17.

 Method according to claim 16, wherein the extruded profile has a part of the base (12) having a lower face defining an internal face, and an upper face defining an external face, reinforcing the reinforcing band the tube against radial crushing loads and the reinforcement band separating the inner face from the fluid contained in the tube.

18.

 Method according to any of claims 16 or 17, further comprising the step of encapsulating the reinforcing band.

19.

 Method according to claim 16, wherein the extrusion and introduction steps take place together in an extrusion head.

twenty.

 Method according to claim 16, further comprising the step of joining a sheet (50) to the base part, the sheet (50) having a Young's modulus and a strength greater than those of the plastic band.

twenty-one.

 Method according to claim 20, wherein the sheet (50) is extruded into the head, in the part of the base of the web of composite material (10).

22

Method according to claim 16, which has additional stages between the introduction and helical winding stages, the additional steps comprising:

directing the band of straight composite material (10) to a reel having a hub that rotates about a substantially horizontal axis, the part of the base of the band being directed to the underside of the hub; propel the reel in order to pull the band (10) of composite material, straight, towards the reel, to wind the band around the reel hub from its lower face; transport the reel to the construction site; Y unwind the reel band.